Taking The Nokton 50/1.1 Down To 0.7m...

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P. Lynn Miller

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Since I have successfully modified my Nokton 50/1.5 to focus down to 0.7m instead of the factory limited 0.9m, my next project is to modify my Nokton 50/1.1 to focus to 0.7m.

First things, first... I want to know if the modification will be worth effort, so I am having a 1.1mm spacer machined that will sandwich between the lens mount and the lens body, which should extend the lens far enough to decouple the rangefinder. I will set-up the tripod and take some test shots at the distance just before the lens decouples to check the performance of the Nokton 50/1.1 at distances less then 1m and wide-open. If the lens does not perform well, then I will not bother with the modification, but I am hoping for the same result as the Nokton 50/1.5 which just blew me away at 0.7m.

I should have all the bits on Friday to test the Nokton 50/1.1... I will be sure to take some photos of the process.

Stay tuned...
 
The first phase of modifying the Nokton 50/1.1 to close focus to 0.7m has begun... setting up the lens to test performance at 1m and closer.

Today I picked up a set of spacers made for me by a machinist friend... 0.9mm, 1.0mm, 1.1mm, 1.2mm, and 1.3mm. They been drilled so I can install the spacer between the lens mount and the lens body.

Here is the lens with the mount removed and the spacers...

nokton5011_07_101.jpg


Here the spacer has been mated to the lens mount, ready to be reinstalled on the lens...

nokton5011_07_102.jpg


Here is the Nokton with the spacer installed and ready for close-focus testing...

nokton5011_07_103.jpg


A 1mm spacer extends the lens to the point where the lens barely decouples, maybe a degree of slack at the most.

I am off to spend some time with some friends, so I will use the lens tonight as a limited range lens. I will set-up the tripod tomorrow and shoot the classifieds to check how the Nokton holds up when focused to 0.7m and wide-open.

Stay tuned...
 
Oh dear,

that might be fun.

I love a little lens hacking from time to time, your solution already seems very nice and clean (unlike mine, most of the time).

Never liked the Nokton much, having owned an M-Hex 50/1.2 in the past, but still: very interested!
 
I'm confused, I thought there were 2 methods -

1. With spacer shim only, between lens and adapter, for close focus, but maxed out at 8 feet or so, not requiring flange to be removed from lens.

2. The internal stopper movement version, allowing .7m to infinity, but requiring extensive dismantling and machining.

This seems to be a variant of process 1? What is the max focus for this setup?
 
This is the F1.1 lens, not the F1.5 lens.

The lens being modified is M-Mount, so the spacer needs to be between the main body of the lens and the mount of the lens.
 
OK, Thanks Brian

OK, Thanks Brian

I understand now. Wow, are you going to go through the whole CV 1m line??

The 35/1.2 focusing to .7m would be interesting!

Brian Sweeney said:
This is the F1.1 lens, not the F1.5 lens.

The lens being modified is M-Mount, so the spacer needs to be between the main body of the lens and the mount of the lens.
Click to expand...
 
This trick will only work with normal lenses where the RF Cam moves 1:1 with the optics. A "Slope and offset" type deal, if the slope is 1 then the offset does what you want it to. The 35mm lens does not move 1:1, so it would be off.

Lynn's elegant solution for the 50/1.5, moving the internal stop for close-focus, might work with the other lenses.
 
Got it

Got it

Thanks Brian, I recall you mentioning this in another thread. Makes sense.

Is there a way to calculate what the far end of focus will be with a shim only method?

When some lenses focus past infinity, would those be ideal lenses to shim, or is their focusing barrel just rotated and they actually focus further than min. distance?

I only had one lens that did that, but since had it fixed, so now all of my lenses stop at infinity.

Brian Sweeney said:
This trick will only work with normal lenses where the RF Cam moves 1:1 with the optics. A "Slope and offset" type deal, if the slope is 1 then the offset does what you want it to. The 35mm lens does not move 1:1, so it would be off.

Lynn's elegant solution for the 50/1.5, moving the internal stop for close-focus, might work with the other lenses.
Click to expand...
 
There is a way to compute the error, and it grows fairly quickly.

1/backfocus+1/frontfocus= 1/focallength

figure the RF cam is calibrated for 51.6mm focal length, and the lens is actually 35mm. You can compute the error as you use a shim.

For example- if you put a Jupiter-3 with its 52.4mm focal length, you get ~0.1mm error in the focus throw of the lens. That is typically the thickness of the shim required to make a J-3 work well on a Leica. A 35mm FL lens is going to walk off very quickly.
 
In theory, though, how much infinity do you really need with a lens like this? I don't tend to use superspeed 50's for landscape, even urban landscape. Or maybe what you are saying is that the alteration would make the lens off at all distances, but not by the same amount at every distance. That's a tough combo for a lens with narrow DOF being used wide open.

Bemused and impressed at the same time,

Ben
 
in theory ...

in theory ...

you only need the smallest amount of infinity to be good 😎

In practice, I think it's going to depend on ones willingness to swap lenses on and off unless they're setting their rig up on a tripod in a studio like setting.

I've never used hacked extended min focus RF lenses, so I think Lynn and Brian will be able to tell us shortly, but I have used an M42 lens on a Nikon F3 SLR that didn't focus to infinity and it was the most frustrating thing.

I think that with these mods, a live-view 4/3, NEX or at minimum, some digital body with instant feedback will be most useful ...

Benjamin Marks said:
In theory, though, how much infinity do you really need with a lens like this? I don't tend to use superspeed 50's for landscape, even urban landscape. Or maybe what you are saying is that the alteration would make the lens off at all distances, but not by the same amount at every distance. That's a tough combo for a lens with narrow DOF being used wide open.

Bemused and impressed at the same time,

Ben
Click to expand...
 
ampguy said:
y
I've never used hacked extended min focus RF lenses, so I think Lynn and Brian will be able to tell us shortly, but I have used an M42 lens on a Nikon F3 SLR that didn't focus to infinity and it was the most frustrating thing.

I think that with these mods, a live-view 4/3, NEX or at minimum, some digital body with instant feedback will be most useful ...
Click to expand...

No question, but then again with a live-view camera like the ones you mentioned, it would be a lot simpler to machine a thin extension tube. This would solve your close focus problem when it was an issue without the need to do anything "behind the mount."

Ben Marks
 
Results are in...

But first here are the technical details -

Leica M5
Nokton 50mm f1.5
Efke KB25
Rodinal 1:25
Epson V500 scanner

All images were shot off the tripod at maximum aperture of 1.1 and at 0.75M from the film plane.

The Efke KB25 was rated at box speed and developed in Rodinal 1:25 at 20°C for 4:00 minutes with vigorous agitation.

The negatives were scanned on my Epson V500 at 3200dpi as transparencies in .tif format. The .tif files were imported into Photoshop CS4, inverted with CF Systems ColorNeg filter. The files were converted to Black & White with Photoshop B&W command with no filters. All files were adjusted with the same contrast curve. The files were resized to 900 x 600 images with Bicubic Sharper and saved as Highest Quality .jpeg files.

I could only be bothered with one 'test' image...
2010_08_005_007_900.jpg


Again the scanner delivered a mushy scan, so you will have to take my word for it. Under the loupe I had no trouble reading the smallest print over most of the negative. I was surprised at the resolution even though there was fall-off in the corners. Distortion is very apparent, I never noticed it before. The image is softer on the left-side, but I would suspect that I did not have the camera completely parallel to the paper.

The results are more than good enough for me... you be the judge for yourself.

More scans to be posted shortly...
 
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Now for some scans that represent using the Nokton 50/1.1 in practice at less than a meter...

2010_08_005_001_900.jpg

Leica M5 | Voigtländer Nokton 50mm f1.1 | Efke KB25 | Rodinal 1:25 | 4:00 minutes | 20ºC

2010_08_005_012_900.jpg

Leica M5 | Voigtländer Nokton 50mm f1.1 | Efke KB25 | Rodinal 1:25 | 4:00 minutes | 20ºC

2010_08_005_017_900.jpg

Leica M5 | Voigtländer Nokton 50mm f1.1 | Efke KB25 | Rodinal 1:25 | 4:00 minutes | 20ºC

Why Cosina did not make this lens to focus to 0.7m is beyond my comprehension. It is extremely usable at very close focus and wide-open. This really irritates me, it shows a lack of diligence, no that is not the right word, more along the lines of making a great product instead of a good product. Just makes me cranky.

Now the hard work starts, modifying the lens to focus to 0.7m...
 
JSU said:
What a difference a stop makes, I'm more impressed by the Nokton 50/1.5, I would have expected less light falloff with the 50/1.1 racked this far out.

I'm still very seriously considering opening-up my own 50/1.5 to achieve the extra 0.20m of close focus. Lynn, can you further elaborate on your method with these lenses for extending close focus, particularly any pitfalls or surprises for which to be mindful?
Click to expand...

Well... I do not think that anyone knows what to expect as this is the only super-fast 50mm that will focus to 0.7m that I know of. Unless someone has shimmed out a Noctilux, Canon 50/0.95, or Nikkor 50/1.1... so I believe that we are treading on new ground here.

From looking at the negatives, the Nokton 50/1.1 is sharper at close focus than the Nokton 50/1.5 until you get to the corners. Also the lightfall-off is practically the same, the Nokton 50/1.5 has maybe slightly less fall-off, but distortion is where the Nokton 50/1.5 is the big winner. By f1.4, the Nokon 50/1.1 is equally as sharp/or sharper than the Nokton 50/1.5 across the frame right into the corners and has less vignetting than the Nokton 50/1.5. And by f2.0 the Nokton 50/1.1 has no vignetting to my eye.

Taking distortion out of the equation, I would say the Nokton 50/1.1 out performs the Nokton 50/1.5 without even taking into account that the Nokton 50/1.1 is a full stop faster. That is my personal opinion, so take it with a grain of salt.

Let's just say that you cannot blame any problems with your photography on the Nokton 50/1.1.

As for documenting the modification on the Nokton 50/1.5, I have to get another lens in my hands because I am not in the mood to take mine apart again just to take pictures. It was too tedious and I want to spend my time working out the modifications for the Nokton 50/1.1.
 
Great work, really amazing. It is hard to determine why Cosina stopped when they did, I suspect that manufacturers like lots of room in the helical between close-focus stop and screw apart to prevent wobble.

Please document the process when you take it apart. Sometimes I go back to review the images taken during disassembly to help re-assemble. "Sometimes", wish I had.
 
Well done, but like the Noctilux I suspect that most people would not be able to focus this accurately wide open at 0.7m, especially when recomposing. Then people would blame the lens. Limiting the focus to 1m means less chances of people complaining.
 
Of course the modified lens can be used at 1M, but an unmodified lens cannot be used closer. Focussing an F1.1 lens on an RF is easier and more accurate than focussing an F1.2 lens on a Manual Focus SLR at 2ft. People have been doing that for many years.

The example photo's are in focus using the M5's 0.72x finder. My modified M3 would be easier. On an M8, the 1.25x eyepiece would help.
 
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